During the development of Light, I looked for such a battery monitor icon without much luck. My solution was to use gkrellm, remove all the other modules, and use the "invisible" skin. That left me with a nice indicator bar on the desktop that would give the percentage and a "progress bar".

If you set TaskBarShowAPMTime to 0 in the preferences file it shows the percentage of the battery capacity instead of the time. And also a C for Charging and a P for Powersupply.For me it's almost like an icon.

If you set TaskBarShowAPMTime to 0 in the preferences file it shows the percentage of the battery capacity instead of the time. And also a C for Charging and a P for Powersupply.For me it's almost like an icon.